1. Field of the Invention
The present invention relates to an airbag device adapted to be mounted on a vehicle and provided with an airbag and a generally cylindrical inflator for feeding an inflation gas to the airbag to inflate the airbag.
2. Description of Related Art
A known airbag connected with a generally cylindrical inflator includes an airbag body and a flexible reinforcing sheet (reinforcing cloth) disposed inside the redirecting sheet for enhancing heat resistance, as shown in JP2011-201518A, paragraph 0041 and FIGS. 14 and 18. The airbag body includes a main inflatable portion which is inflatable with an inflation gas in such a manner as to separate a front wall from a back wall and a connection port which is formed into a tube for connection with the inflator to admit the inflation gas. The connection port includes a root region which extends from and generally perpendicularly to the main inflatable portion and a tubular region into which the inflator is inserted. The tubular region is formed generally perpendicularly to the root region, thus the connection port is formed into an L shape and mounted on a vehicle in that L shape. The reinforcing sheet is mounted around the inflator inside the connection port for enhancing head resistance. The conventional reinforcing sheet is formed by folding a plain-weave cloth or the like in half and sewing peripheral edges thereof together because that way the reinforcing sheet can be manufactured at a lower cost than a reinforcing sheet formed by one-piece woven technology (as disclosed in JP2006-117109A, by way of example).
The problem with the conventional reinforcing sheet is that it has a crease of the double-folding of the plain-weave cloth on the upper edge facing away from the main inflatable portion of the bag body inside the tubular region of the connection port while a seam by the sewing is disposed in a vicinity of the front edge inside the root region of the connection port disposed away from the inflator.
The inflation gas fed from the inflator flows along an axial direction of the tubular region of the connection port and hits the front edge of the root region of the connection port, and then is redirected towards the main inflatable portion of the bag body. That is, the inflation gas hits the seam of the reinforcing sheet before flowing into the bag body.
Since the seam is likely to be damaged due to hot inflation gas, an improvement in the heat resistance of the reinforcing sheet has been desired.